Engineering, Technology & Applied Science Research

246-250

Authors: S. Bertoldo, C. Lucianaz, M. Allegretti, O. Rorato, A. Prato, G. Perona

The increasing frequency of extreme and very localized precipitation events have been causing landslides, floods and casualties, especially in Sicily, due to its complex orography, and to the presence of densely inhabited areas just at the mouth of small basins. In order to monitor such phenomena with the needed high resolution in time and space, an experimental network of X-band mini-radars, exclusively devoted to monitor rain, has been installed in some parts of Sicily since November 2010. The network is made up by 4 mini weather radars able to acquire a rain map every minute (or even at shorter intervals) with a radial space resolution better than 100 m within a range of up to 30 km. Their low cost and the easiness of installation make such radars ideal for monitoring small areas or even just limited angular sectors, since it is more convenient to install more than one instrument instead of choosing special site locations or spending for installation support. The raw data are immediately processed in real time by the software installed on each radar unit, Cartesian maps are locally produced, compressed and transmitted via GPRS to a server where ad hoc products for the users are prepared and made available on a web site. A few examples of final products and some comparisons with rain gauges are presented.

259-264

Authors: E. V. Vorozhtsov

In this paper, some unsolved problems of the Mathematica software package are documented. At first, it is shown, using a number of examples, that the processing (simplification) of rational-fractional expressions involving powers in the general form, has been implemented in Maple more carefully than in Mathematica. Then, an error in Mathematica is demonstrated, leading to incorrect results at a change of a function’s body. For each example of symbolic or symbolic-numeric computations, alternate routes for solving the emerged problem are proposed (where possible). An added problem, related to Mathematica’s computing speed is documented, employing examples related to two-dimensional gas dynamics problems. It is shown that Mathematica computes rather slowly (about one thousand times slower) compared to a Fortran code.